He also challenged the United Nations to fundamentally reform itself as an institution if it is to remain relevant in the years ahead.

Mr Clegg said:

The effectiveness of multilateral approaches is in question in the wake of the financial crisis, the collapse of the climate change talks in Copenhagen and the stalling of the Doha trade round.

Too many nations and international institutions have been too reticent about promoting enlightened, human values. We need to inject new life into our institutions, and new confidence into the expression of our ideals.

In recent years, our multi-national institutions have sometimes struggled to adapt to the new circumstances. Reform is essential.

The Deputy PM told the assembled world leaders that the Coalition Government would be “hard-headed and realistic” in its approach to the rest of the world and stand as “a beacon of democracy, freedom and law”.

Many of the values that must be at the heart of a new global settlement are in our national DNA - tolerance, fairness, democracy, equality before the law.

But our approach will also be hard-headed and realistic.

Mr Clegg’s speech comes at the end of a week long visit to the US. Earlier this week the Deputy PM spoke at the UN Millennium Development Goals Summit where he called on other nations to keep to their pledges to raise living standards in the developing world.